Combined pulse jet and variable ram jet engine



Oct. 13, 1970 COMBINED PULSE JET AND VARIABLE RAM JET ENGINE Filed May8, 1969 Fig.

J. N. GHOUGASIAN 3 ,533,239

4 Sheets-Sheet 1 Jo/m IV. G'lrougasian INVENTOR.

MM FM L COMBINED PULSE JET AND VARIABLE RAM JET ENGINE Filed May a, 19694 Sheets-Sheet um um aw M an 1. A i; g Q} .7. mm 9 Q k k m NM N7 I VVMQN udnwln v luv, 2 Yr vnb? Q ww m. mm Mn mm mm E MN m w t m m R. m n ma N I A u E m w 1 8 M W G M w B hm K v\ an Oct. 13, 1970 J. N.GHOUGASIAN 3,533,239

COMBINED PULSE JET AND VARIABLE RAM JET ENGINE Filed May 8, 1969 4Sheets-Sheet 5 m V (o r v John N. Ghougasian ENTOR.

BY WWW Oct. 13, 1970 J. N. GHOUGASIAN COMBINED PULSE JET AND VARIABLERAM JET ENGINE 4 Sheets-Shet Filed May 8, 1969 John N. Ghbugasian R. mm,

I m mm United States Patent 3,533,239 Patented Get. 13, 1970 3,533,239COMBINED PULSE JET AND VARIABLE RAM JET ENGINE John N. Ghougasian, 666W. 188th St., New York, NY. 10040 Filed May 8, 1969, Ser. No. 822,980Int. Cl. F02k 7/06, 7/10 U.S. Cl. 60-244 Claims ABSTRACT OF THEDISCLOSURE This invention relates to propulsion engines of the reactiontype and more particularly to a reaction jet engine having pulse jet andram jet modes of operation.

Pulse jet and ram jet engines have distinctly different geometricalconfigurations and components necessary to support operation inaccordance with the generally known principles. Since pulse jet enginesbecome inefficient and inoperative at speeds above 400 m.p.h., they areonly suitable for operation below the higher speed ranges where ram jetengines are most efiicient. Therefore, combined pulse jet and ram jetengines have been proposed in an attempt to provide propelling thrust atboth lower and higher speeds with optimum efficiency. However, enginegeometry suitable for pulse jet operation is incompatible with enginegeometry for ram jet operation. Further, pulse jet engines require acheck valve assembly in the airstream flow path that would beintolerable for ram jet operation. Ram jet engines on the other handrequire the presence of a flame holder in the airstream flow pathincompatible with pulse jet operation. Combined pulse jet and ram jetengines heretofore proposed have therefore involved a plurality ofairstream flow paths and flow blocking valving arrangements in order toincorporate within a single engine separate pulse jet and ram jetsections. Such combined engines involve relatively complex internalengine structure making engine operation less efiicient for both pulsejet and ram jet operational modes as well as adding to the weight of theengine.

The foregoing drawbacks of prior art proposals for combined pulse jetand ram jet engines, have been overcome by the present invention. Animportant object of the present invention therefore is to provide acombined pulse jet and ram jet engine which is inherently less expensiveto manufacture and capable of providing a greater power-toweight ratiofor both pulse jet and ram jet operation than any combined jet engineheretofore proposed.

In accordance with the present invention, the internal geometry of areaction jet engine is altered in order to accommodate both pulse jetand ram jet operation while components respectively associated withpulse jet and ram jet operation are selectively inserted and retractedfrom a single airflow passage common to both operational modes. Inchanging the internal geometry of the engine, an important and criticalfeature resides in an axially shiftable nozzle throat formation which isin a forward position rearwardly limits the combustion zone for pulsejet operation and in a rearward position dimensionally enlarges thecombustion zone and converts the tail end portion of the engine to anexit nozzle suitable for ram jet operation. Also, a retractable checkvalve assembly is positioned within the intake section of the engine forpulse jet operation while a retractable flame holder is positioned at aforward end of a combustion zone for ram jet operation. Air inflow tothe engine is changed by a variable geometry intake section in order toaccommodate pulse jet and ram jet operation in conjunction with theother internal engine changes aforementioned.

These together with other objects and advantages which will becomesubsequently apparent reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawings forming a part hereof, whereinlike numerals refer to like parts throughout, and in which:

FIG. '1 is a top plan view of a combined pulse jet and ram jet engineconstructed in accordance with the present invention.

'FIG. 2 is a longitudinal sectional view taken substantially through aplane indicated by section line 22 in FIG. 1.

FIG 3 is a transverse sectional view taken substantially through a planeindicated by section line 3--3 in FIG. 2.

FIG. 4 is a transverse sectional view similar to FIG. 3 showing thecheck valve assembly being angularly repositioned for retraction.

FIG. 5 is a longitudinal sectional view through the engine converted toram jet operation.

FIG. 6 is a sectional view taken. substantially through a planeindicated by section line 66 in FIG. 5.

FIG. 7 is a partial longitudinal sectional view of the engine showingthe flame holder angularly orientated in preparation for retraction.

FIG. 8 is a partial longitudinal sectional view showing the flame holderin retracted position.

FIG. 9 is a transverse sectional view taken substantially through aplane indicated by section line 9 -9 in FIG. 5.

FIG. 10 is an enlarged partial sectional view taken substantiallythrough a plane indicated by section line 1010 in FIG. 2.

FIG. 11 is an enlarged partial sectional view taken sub-- stantiallythrough a plane indicated by section line 11-11 in FIG. 10.

FIG. 12 is a partial longitudinal sectional View showing the intakeportion of the engine.

FIG. 13 is a front elevational view of the intake portion of the engine.

FIG. 14 is a transverse sectional view taken srbstantially through aplane indicated by section line 14---14 in FIG. 12.

FIG. 15 is a transverse sectional view similar to that of FIG. 4 showinganother form of check valve assembly in a partially retracted condition.

FIG. 16 is a partial sectional view taken substantially through a planeindicated by section line 1616 in FIG. 15.

Referring now to the drawings in detail, FIG. 1 illustrates one exampleof a combined jet reaction engine constructed in accordance with thepresent invention and generally referred to by reference numeral 10. Theengine includes a generally tubular housing 12 extending from an airinlet end 14 to an outwardly flaring tail end section 16 from whichthrust producing gases are discharged. Airfoil shaped projections 18 and20 extend laterally from and intermediate the ends of the housing.Another pair of projections 22 and 24 extend laterally from the housingperpendicular to and spaced forwardly of the projections 18 and 20. Thelaterally extending projections enclose component receiving cavities aswill be explained hereafter.

Referring now to FIG. 2, the jet engine 10 is shown conditioned forpulse jet operation. The housing 12 is internally formed with an annularintake passage section 26 formed about a center body 28 coaxiallypositioned within the housing by supporting struts 30. The passagesection 26 conducts the inflow of air to a check valve assembly 28associated with pulse jet operation. The constructional details of checkvalve assembly itself are well known and form no part of the presentinvention. However, in accordance with the present invention, the checkvalve assembly 28 is operatively positioned coaxially within the housingand is displaceable from this operative position as will be hereafterexplained. Further, the check valve assembly 28 is operativelypositioned within the flow passage at a location forwardly of a flameholder 30 which is operatively positioned as shown in FIG. for ram jetoperation.

With continued reference to FIG. 2, the flow passage extendingrearwardly from the location of the flame holder 30 is enclosed by ahousing section 32 of relatively constant diameter and of a preselectedlength terminated by the outwardly flaring tail end section 16. A nozzlethroat member 34 is adjustably positioned within the housing section 32between a forward, pulse jet position as shown in FIG. 2 and a rearwardram jet position as shown in FIG. 5.

The check valve assembly 28 is positioned by means of a telescoping typeof power operated piston device 36. Thus, the check valve assembly maybe retracted by the piston device into a receiving cavity 38 formed inthe projection 22 for this purpose as shown in FIG. 5. In one embodimentof the invention, before the valve assembly is retracted into itscavity, it is angularly rotated by 90 degrees to a position as shown inFIG. 4. Toward this end, one of the extensible piston rods 40 associatedwith the piston device 36, has a sector gear 42 connected thereto asmore clearly seen in FIGS. and 11 for meshing engagement with apiniongear 44 driven by a motor 46. Thus, the check valve assembly 28 may beangularly oriented for retraction into its cavity 38 or angularlydisplaced to an operative position after it is extended by the pistondevice 36 into the flow passage.

FIGS. and 16 illustrate an alternative arrangement for retracting andoperatively positioning a check valve assembly constructed in twoseparable half sections 28' so that each half section may be retractedinto cavities 38' dsposed in both of the projections 22 and 24. Poweroperated piston devices 36' are accordingly mounted within eachprojection 22 and 24 and connected to the valve assembly half sections28'. Angularly orientating means will of course also be associated withthe piston devices 36 as described in connection with FIGS. 2, 10 and11.

A retracting mecahnism 48 similar in construction and operation to theretracting mechanism for the check valve assembly hereinbeforedescribed, may be associated with the flame holder 30 for positioningthereof between an operative position as shown in FIG. 5 and aninoperative position as shown in FIG. 8. Accordingly, in one embodimentof the invention, the lateral projection is provided with a receivingcavity 50 into which the flame holder is displaced after it is angularlyorientated from its operative position as shown in FIG. 5 to the intermediate position as shown in FIG. 7.

The nozzle throat member 34 is designed to form a throat restrictionwithin the flow passage of the housing 12. The location of this nozzlethroat member will change the internal geometry of the flow passage soas to accommodate either pulse jet or ram jet operation. A positioningmechanism generally referred to by reference numeral 52 is thereforeoperatively connected to the throat member 34 and is enclosed within alongitudinal projection 54 on the housing. One form of positioningmechanism as illustrated in FIGS. 2 and 5, includes an elongated,externally threaded actuating shaft 56 rotatably mounted within theenclosing projection 54 and threadedly extending through a nut element58 connected to the throat member 34. The nut element extends through aguide slot 60 formed in the housing section 32 so as to axially move thethroat member between its two operative positions upon rotation of theactuating shaft 56 by a motor 62. The throat member as will be explainedhereafter, limits the rearward end of the combustion zone in either ofits operative positions.

In order to control the inflow rate of air so as to accommodate bothpulse jet and ram jet operation, the center body 28 within the intakepassage section 26, mounts an axially shiftable nose element 64 havingradially extending guide fins 66 slidably received in guide slots 68formed in the center body as more clearly seen in FIG. 14. The noseelement may be provided with a rearwardly extending piston portion 70slidably received within a pressure controlled chamber 72 through whichthe nose element may be extended forwardly or retracted rearwardly. Theguide fins 66 are operative to axially displace a forwardly converging,truncated conical element 74.

When the nose element 64 is fully retracted, as shown in FIG. 2, theconical element 74 will be resting on the forward conical portion of thecenter body 28 while the guide fins 66 will be fully retracted withinthe center body so as to admit a maximum quantity of air into the inletend of the housing. The flow area of the inlet end 14 when opened by amaximum amount will be dimensioned to conduct the requisite quantity ofair into the engine for pulse jet operation. When the engine isconverted to ram jet operation at subsonic speeds above 400 m.p.h., thenose element 64 is extended to an intremediate position as shown in FIG.12 so that the guide fins 26 forwardly displace the conical element 74to thereby reduce the inlet opening at the forward inlet end 14. In thesupersonic speed range, the nose element 64 is fully extended to theposition shown in FIGS. 5 and 6 wherein the conical element 74 engagesthe rim of the inlet opening so that the inflow of air is restricted tothe smaller opening at the inlet end of the conical element 74, as moreclearly shown in FIG. 13.

Referring now to FIG. 2 in connection with pulse et operation of theengine, it will be apparent that with the inlet end 14 fully opened, theinflow rate of air will be sufiicient to obtain a proper fuel-airmixture within the combustion zone located between the check valveassembly 28 and the throat member 34. Fuel is injected through a fuelinjector 76. Following initial air intake, the fuel-air mixture withinthe com-bustion zone is ignited by the spark plug device 78. As is wellknown in connection with pulse jet engines, when combustion occurswithin the combustion zone, the check valve assembly 28 is closed sothat gases resulting from combustion are propelled rearwardly from thecombustion zone through the housing section 32 and exit through the tailend section 16 to impart thrust to the engine. As is also well known inconnection with pulse jet operation, gases continue to exhaust from thetail end section of the engine because of momentum after the pressuregenerated by combustion within the combustion zone has returned toatmospheric value. When the pressure within the combustion zone drops toa low point below atmospheric value, the check valve assembly 28 permitsreentry of air through the inlet end 14 while air also enters the tailend section of the engine to increase the air mass within the combustionzone. Re-ignition of the new fuel-air mixture within the combustion zoneoccurs because of residual hot gases to begin a new cycle. Thus,periodic combustion occurs at a predetermined frequency to generate apulsating thrust. The length of the housing section 32 is thereforeselected in order to obtain resonance with the pulsating combustionfrequency. Further, in View of the re-entry of air through the tail endsection 16, during each pulse cycle, the tail end section must flareoutwardly as shown.

It will be appreciated by those skilled in the art, that a pulse jetengine is economical and eflicient at reatively low speeds and willtherefore be suitable in accordance with the present invention to startand accelerate any vehicle being propelled by the engine up to a speedof 400 mph. beyond which the efliciency of pulse jet operation dropssharply. Since a pulse jet engine becomes inoperative at 500 mph andabove, in accordance with the present invention the engine is convertedfrom pulse jet operation to ram jet operation at about 400 mph. This isaccomplished by retracting the valve assembly 28 from the single flowpassage of the engine and operatively positioning the flame holder 30within the flow passage as shown in FIG. 5 together with movement of theexit throat member 34 to its rearward position thereby converting thetail end section 16 to an exit nozzle. Also, in view of the high speedof operation, the inlet opening is reduced by forward displacement ofthe conical element 74. Further, since pulse jet operation of the engineis only utilized below cruising speeds, the less frequent use of thevalve assembly 28 will prolong its life in view of its protectiveenclosure within cavity 38.

The geometry of the inlet end of the engine is changed for ram jetoperation as aforementioned in order to match the inlet flow area to theexit nozzle flow area so that outflow equals inflow to avoid pile up atthe entrance to the diffuser passage section 26. The throat member 34may therefore be dimensioned to provide the proper exit nozzle geometryfor ram jet operation not inconsistent with pulse jet operation when thethroat member is in its forward position as shown in FIG. 2. Thus, as inthe case of most ram jet engines, as the air enters the inlet end of theengine, it increases in pressure most rapidly as its velocity decreasesand its temperature increases. Within the diffuser flow section 26, theair increases in pressure and temperature at a lower rate as itsvelocity continues to decrease thereby maintaining a constant totalenergy as the kinetic energy is transformed to pressure energy. Prior toentering the combustion zone, the forward end of which is limited by theflame holder 30, the air is mixed with fuel injected through anotherfuel injector 80 spaced forwardly of the fuel injector 76 utilized forpulse jet operation. Ignition of the fuel-air mixture within thecombustion zone may be started by the spark plug 82, the combustion zoneextending from the flame holder 30 to the throat member 34- forming partof the exit nozzle. The heat energy added to the fluid within thecombustion zone due to combustion, causes a sharp rise in temperaturethereof and an increase in velocity while its pressure decreases from amaximum value as the air enters the combustion zone. The flow of gasesthen undergoes a sharp rise in velocity as it is discharged through theexit nozzle accompanied by a reduction in pressure and temperature, asin the case of most ram jet engines.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly all suitable modifications and equivalentsmay be resorted to, falling within the scope of the invention.

What is claimed as new is as follows:

1. In a combined pulse-jet and ram-jet engine, a tubular housing havinginlet and outlet end portions between which a single flow path isestablished, internal throat means mounted by the housing fordimensionally limiting a combustion zone upstream thereof within saidflow path, and positioning means connected to the throat means fordisplacement thereof between a pulse-jet position spaced upstream of theoutlet end portion and a ram-jet position at the outlet end portion ofthe housing within said flow path.

2. The combination of claim 1 including variable geometry intake meansmounted in the inlet portion of the housing upstream of the combustionzone within said flow path for varying the inflow area of the inletportion to accommodate both pulse-jet and ram-jet operation.

3. The combination of claim 2 including a flame holder device fordimensionally limiting the combustion zone downstream thereof duringram-jet operation, and means mounted by the housing for retracting theflame holder device from the flow path during pulse-jet operation.

4. The combination of claim 3 including check valve means forintermittently blocking inflow to the combustion zone during pulse-jetoperation and means mounted by the housing for retracting the checkvalve means from the flow path during ram-jet operation.

5. The combination of claim 4 wherein each of said retracting meansincludes a power operated positioning member movable transversely ofsaid flow path, a projection mounted on the housing having a receivingcavity extending laterally from the flow path, and cavity aligning meansfor angularly displacing the positioning member.

6. The combination of claim 2 including check valve means forintermittently blocking inflow to the combustion zone during pulse-jetoperation and means mounted by the housing for retracting the checkvalve means from the flow path during ram-jet operation.

7. The combination of claim 1 including check valve means forintermittently blocking inflow to the combustion zone during pulse-jetoperation and means mounted by the housing for retracting the checkvalve means from the flow path during ram-jet operation.

8. The combination of claim 7 wherein said retracting means includes apower operated positioning member connected to the check valve means, aprojection mounted on the housing having a cavity receiving the checkvalve means in a retracted position laterally of the flow path, andvalve orientating means connected to the positioning member forangularly aligning the check valve means with the cavity to enter thesame when displaced to the retracted position by the positioning member.

9. In a combined pulse-jet and ram-jet engine, a tubular housing havinginlet and outlet end portions between which a single flow path isestablished, means mounted by the housing for dimensionally limiting acombustion zone upstream thereof within said flow path, check valvemeans for intermittently blocking inflow through the flow path to thecombustion zone during pulse-jet operation and means mounted by thehousing for retracting the check valve means transversely from the flowpath without dimensional change thereof to a retracted position forramjet operation.

10. The combination of claim 9 wherein said retracting means includes apower operated positioning member connected to the check valve means, aprojection mounted on the housing having a cavity receiving the checkvalve means in said retracted position laterally of the flow path, andvalve orientating means connected to the positioning member forangularly aligning the check valve means with the cavity to enter thesame when displaced to the retracted position by the positioning member.

References Cited UNITED STATES PATENTS 2,677,232 5/ 1954 Collins 60-2442,683,961 7/1954 Britton 60244 2,745,248 5/ 1956 Winter 60--24@l-2,850,872 9/1958 Stockbarger 60244 3,078,660 2/1963 Hansel 60-39.77

DOUGLAS HART, Primary Examiner U.S. C1.X.R.

